Heater for pre-heating fuel with a heated liquid

ABSTRACT

A pre-heater for fuel includes a corrugated tubing for passing hot water therethrough. An outer cylinder forms a jacket around said corrugated tubing to form a chamber to receive therethrough the fuel to be heated. The heat from the hot water is transmitted through the corrugated tubing to heat the fuel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Temperatures below zero cause problems in the operation of dieselengines because they tend to cause wax formations in the fuel for theengine. The flaky wax formations tend to clog the filters in the fuelflow system and prevent proper operation of the engine. To overcome thisproblem, it is necessary to preheat the fuel before it is applied to theengine in order to avoid clogging of the filter system.

2. Prior Art

Previous pre-heaters have used hot water in the radiator of the vehicle.In one such heater, the fuel line was passed through an outer largerconduit which jacketed the inner conduit. The hot water in the outerconduit heated the fuel in the fuel line as it passed therethrough. Inthese heaters, the fuel remained in its original line, which wasrelatively small in diameter and therefore did not become adequatelyheated.

In a copending application of the same inventor and assigned to the sameassignee as the present invention entitled "A Heater for Pre-HeatingFuel", Ser. No. 967,523, filed Dec. 7, 1978, now U.S. Pat. No. 4,208,996there is described another type of pre-heater which is generally cubicalin shape and divided into two separate chambers, with heated water inone chamber and the fuel in the other. This provided a greater area forthe fuel to be heated.

While the pre-heater described in the aforementioned application offeredadvantages over the prior art, it was found that by changing thephysical structure of the pre-heater from substantially rectangularenclosures to cylindrical enclosures and providing a special type ofheat transmitting member between the water and the fuel that a morecommercially acceptable heater of higher efficiency could be made.

OBJECTS OF THE INVENTION

It is an object of this invention to provide an improved heater forpre-heating fuel with a heating fluid which provides a maximum heattransfer from the fluid to the fuel.

It is a further object of this invention to provide an improved heaterfor pre-heating fuel with a heating fluid in which maximum heating ofthe fuel is obtained in a minimum space.

It is still a further object of this invention to provide an improvedheater for pre-heating fuel with a heating fluid in which the capacityof the heater may be increased or decreased without extensive retooling.

BRIEF SUMMARY OF THE INVENTION

In accordance with the present invention a pre-heater for heating fuelincludes a corrugated tubing for passing heated water therethrough. Anouter cylinder forms a jacket around the corrugated tubing to form achamber to pass the fuel therethrough. Heat from the water istransmitted through the corrugations of the tubing to heat the fuel. Thecorrugations provide a maximum heat transfer area between the water andthe fuel.

Other objects and advantages of the present invention will be apparentand suggest themselves to those skilled in the art, from a reading ofthe following specification and claims, taken in conjunction with theaccompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a pre-heating system for fuel ofthe type involving the present invention;

FIG. 2 is a cross-sectional side view of a pre-heater device used in thesystem illustrated in FIG. 1, and

FIG. 3 is an end view of the pre-heater device illustrated in FIG. 2.

DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a pre-heater 10 comprises a corrugated tubing 12forming a passageway 14. A cylindrical member 16 surrounds and forms ajacket for the corrugated tubing 12 to provide a chamber 18 between theinner surface of the member 16 and the outer surface of the tubing 12.

A diesel engine system of a vehicle which may use the present invention,generally includes a radiator. Hot water is circulated by a pump from aradiator or other source 20 through an inlet conduit 22 through thepassageway 14 in the corrugated tubing 12 and back to the source 20through a conduit 24.

During subzero weather when wax tends to build up in the liquid fuel andtherefore requires pre-heating, the fuel is fed from a fuel tank 19 to alift pump 21. The pump 21 forces the fuel through an inlet conduit 26into the chamber 18. The corrugated tubing 12 is highly conductive ofheat to permit the heat from the hot water to be transmitted into thechamber 18.

The corrugated tubing 12 provides a maximum area for heat transmission.Greater heat transmission is achieved not only because of thecorrugations, but because the circular tubing provides a greater area ofcontact for the fuel to be heated as opposed to a flat heat transmissionmember. The increased heating efficiency resulting from the corrugationsand circular shape makes it possible to provide the same amount ofpre-heating in smaller units than when cubical or rectangular typeenclosures are used.

The fuel in the chamber 18 passes through an outlet conduit 28 to afilter 30. This is the filter that tends to clog if wax forms in thefuel. When the fuel is heated sufficiently, the tendency of wax buildingup in the fuel is minimized and the filter 30 will not tend to clog.

After passing the filter 30, the heated fuel is passed through a conduit32, through an injection pump 34, through a conduit 36 and finally intothe engine cylinders 38. Except for the preheater 10, and connectionsthereto, all the blocks mentioned are conventional, found in many dieselengine systems and therefore not described in detail.

Referring to FIGS. 2 and 3, the corrugated tubing 12 is centrallydisposed within the cylindrical member 16 to form the chamber 18completely around its circumference. The member and 16 and corrugatedtubing 12 may be readily made into different lengths, i.e., made longeror shorter, to accomodate different capacities for heating. Making thesemembers longer or shorter does not require extensive modification of thedies for making them. The parts preferably are made of stainless steel.

The ends 40 and 41 of the corrugated tubing 12 comprise circular flatsurfaces to permit welding connections to the other elements of theheater 10. The main surface of the cylindrical member 16 includeinwardly extending angular portions 42 and 44 terminating at circularend sections 46 and 48, respectively. The inner surface of the sections46 and 48 are dimensioned to engage the outer surface of the endportions 40 and 41, respectively, of the corrugated tubing 12.

Circular end closures 50 and 52, including central openings 51 and 53therein, include outwardwardly projecting circular perpendicularsections 54 and 56 respectively. The end closures 50 and 52 aredimensioned to fit into the end openings of the corrugated tubing 12 sothat the outer surfaces of the perpendicular sections 54 and 56 engagethe inner surfaces of the ends 40 and 42 respectively, of the tubing 12.The end sections 46, 48, the ends 40, 41 and the sections 54, 56 overlapeach other so that the respective groups of three surfaces may bereadily welded together. The advantage of this is that if any one of theweld joints breaks to cause either the hot water or fuel to leak, itwill leak to the outside of the housing of the pre-heater 10. Thus,there is no liklihood of damage to the engine as a result of watermixing with the fuel.

Connectors 58 and 60 are welded to the end closures 50 and 52respectively. These connectors are aligned with the central openings 51and 53 in the end closures and are adapted to receive the conduits 22and 24, respectively (FIG. 1). The outer cylinder 16 include openings 62and 64. Connectors 66 and 68 are welded to the cylinder 16 in alignmentwith the openings 62 and 64. The connectors 58 and 60 are disposed toreceive the conduits 26 and 28, respectively.

In the preheater illustrated, the cylinder 16 forming the chamber 18with the tubing 12, has its outside surface exposed to ambienttemperature. When the temperature of the fuel rises to the temperatureof the hot water, the fuel transmits heat through the cylinder 16. Atabout 150° F., for example, the temperature of the fuel will stoprising. The limit in fuel temperature rise prevents the engine fromlosing horsepower during operation. Therefore, there is no need for anoperator to operate shutoff valve when he drives from areas of hightemperature to areas of low temperature.

The pre-heater of the present invention has all the advantages of theheater described in the aforementioned application. In addition, it hasthe added advantage that for equal efficiency, it may be made smaller.This is because the circular corrugated tubing provides the same area ofheat transmission in a smaller space. Also, the pre-heater of thepresent invention may be built for different capacities without greatlymodifying the tooling involved. Finally, in most cases, it is generallyeasier to connect the hot water in an aligned centrally disposedpassageway. With respect to the fuel, it has to go from relatively thinfuel lines into a large chamber for maximum heating and therefore theirregular path of the fuel is less important.

What is claimed is:
 1. A pre-heater for heating fuel with a heatedliquid comprising:a. a corrugated tubing forming a first chamber toreceive said heated liquid therethrough; b. an outer cylinder forming ajacket around said corrugated tubing and connected towards the ends ofsaid corrugated tubing to form a second chamber to receive said fueltherethrough: c. inlet and outlet means connected to said corrugatedtubing to pass said heated liquid therethrough. d. second inlet andoutlet means connected to said second chamber to pass said fueltherethrough: e. said corrugated tubing and said cylindrical member eachinclude flat circular overlapping extensions at the ends thereof securedtogether and extending to the outside of the pre-heater and away fromthe fuel in said chamber and the heating liquid in said corrugatedtubing; and f. enclosures having flat circular portions extending in thesame directions as said overlapping extensions and secured within theextensions at the ends of said corrugated tubing, said enclosures havingcentrally disposed openings leading to said inlet and outlet means forpassing said heated liquid therethrough; whereby heat from said heatingliquid is transmitted through said corrugated tubing to heat said fuelin said chamber.
 2. A pre-heater as set forth in claim 1 whereinopenings are provided in said cylindrical member leading to said secondinlet and outlet means for said fuel.
 3. A pre-heater as set forth inclaim 2 wherein the extensions of said corrugated tubing, the extensionsof said cylindrical member and the circular portions of said closuresare welded together and overlap each other, whereby the breaking of anyone weld joint will cause one or the other of said fuel or said heatedliquid to leak to the outside of said pre-heater without any mixing thefuel with the heated liquid.